Bottles and cylindrically shaped vessels are commonly used as containers of various goods for sale in the retail market.
There are inherent disadvantages to bottles and cylindrical containers. For example, they generally have poor stacking characteristics, and cylinders which are much taller than they are wide can be easily tipped and rolled.
The use of large plastic bottles often made of polyethylene terephthalate in the soda pop industry has grown in recent years. Plastic bottles, being more shock and impact resistant than glass, can be more safely used for larger volumes, especially for liquids under pressure.
The systems used in packaging and shipping bottles should allow such bottles to be shipped, stacked, stored and displayed in stores without the need to move the bottles into separate units for each function required.
Certain conventional bottle cases provide a frame which is taller than the bottles. Such cases are provided with internal dividers which minimize bottle contact. They can be stacked to provide convenient storage means for bottles. These cases are heavy, bulky to store and cannot easily be used for display purposes, since they hide the bottles inside. Such cases are still used where display is not important.
A tray has been developed which provides cups for holding the lower portion of a bottle, allowing the remainder of the bottle to be exposed. Such a tray is shown in Canadian patent No. 1,160,603.
Such trays are designed to permit stacking in a grocery store display. However, in order to display the bottle, the cups of such trays rise to only one-third of the bottle height so that the cup does not hold the upper two-third of the bottle.
On the one hand, such cups must snugly fit the bottles to keep the bottles within the tray as the tray is transported and moved along steep inclines in bottle packaging facilities. On the other hand, the bottles must be removable from the tray by consumers when the trays are stacked as a display in the grocery store and they must be able to be drop-packed into the tray by a machine.
Thus the bottles must at one time be held snugly and at the same time be relatively easily placed in and removed from the tray.
The tray of Canadian Patent No. 1,160,603 provides a relatively rigid tray with rigidly fixed cups. In order to provide space for insertion and removal, the cups are made slightly larger than the bottle, and side wall "grippers" are added to the walls of the cups at discrete locations to create a snug fit. This system puts localized pressure on the side wall of a bottle only at discrete locations which is undesirable.
In fact, commercially, Canadian Patent No. 1,160,603 is not in common use with the side wall grippers. Trays are on the U.S. market which are similar to those disclosed the in the Canadian patent. However, such trays are made with cups of exactly the same diameter as the plastic bottles they are designed to hold and therefore with no side wall grippers. The structure of this tray is purposely designed to be rigid to securely hold and grip the lower one-third of the bottle. While this holds the bottles securely, it creates problems inserting and removing such bottles from the tray.
Bottle dimensions vary slightly from bottle to bottle. Under the constant pressure of carbonated contents, large plastic bottles tend to swell. This effect may be exaggerated at elevated temperatures. Thus bottles which are even slightly oversize can severely bind in rigid tray.